<?php
/**
 * Created by PhpStorm.
 * User: Administrator
 * Date: 2016/8/10
 * Time: 12:34
 */
abstract class DB_Db {
    protected static $_link;
    protected $param;
    protected $mysql_addr;

    abstract protected function disconnect();
    abstract public function query($sql);

    public function __destruct()
    {
        if (self::$_link instanceof self) {
            $this->disconnect();
        }
    }

    private function __clone(){}
}